code: def set_backend(backend):
      """
      Set utils.image_utils` backend module.
      If the backend which you specify is not installed in your environment, Exception is raised.
  
      Args:
          backend (str): the name of image_utils` backend
      """
  
      backend_manager.set_backend(backend)
  
file_path: nnabla/python/src/nnabla/utils/image_utils/__init__.py
imports: from __future__ import absolute_import
  import numpy
  from .backend_manager import backend_manager
  from .backend_events.common import rescale_pixel_intensity
label_desc: Use image node_id 1 for calling a global function with example usage: set_backend(backend) without return types